Pumping stations of the above mentioned type are known in the art and generally have a supply line or conduit through which the cooling and lubricating fluid containing particulate matter is delivered, a collecting container connected to the supply line, and a pump communicating with the collecting container. A discharge line is connected to the pressure output side of the pump. Such generally known pumping stations are used in connection with machine tools, such as boring, cutting, or milling machines, for pumping away from the machine tools, for example through pipe conduits, the cooling and lubricating fluid that contains any chips or shavings arising during the chip-removal machining of workpieces. Separate equipment arranged at a separate location will then separate the particulate matter such as cutting chips from the cooling and lubricating fluid, so that the fluid can be reused in the machining process.
European Patent Publication 0,518,095 discloses a pumping station in which comminuted machining chips are directed into a catching or collecting container by means of the flow of the cooling and lubricating fluid. The floor of the collecting container has a slight pitch or slope down to the deepest point of the floor of the container, where a pump is arranged. Thus, the mixture of cooling and lubricating fluid with machining chips therein is conveyed by gravity into the deepest portion of the floor of the container so that the fluid and chips together will be sucked into the pump.
In order to reliably convey machining chips and the like into the suction area of the pump even when there is a relatively low proportion or flow rate of the cooling and lubricating fluid, it was discovered in the art that it is necessary to use a funnel-shaped collecting container having relatively steeply sloped side walls. Due to such relatively steeply sloped side walls, the machining chips are reliably conveyed by gravity into the suction area of the pump arranged deep within the base of the container.
In the above mentioned known pumping stations, it has been recognized as a disadvantage that either the reliable conveyance of machining chips can only be achieved with relatively low supply volume flows of the chips, or the collecting containers must have a relatively high total structural height to provide for a sufficiently steep slope of the walls and a sufficient collecting volume. In order to reduce the total structural height of the apparatus above floor level, it has previously been typical to arrange or recess the known pumping stations into or below the floor level. However, in view of the danger of polluting ground water resources in the event of any leakage, and thus as required by environmental protection regulations, the pumping stations arranged below floor level in this manner have required a double-walled collecting container securely anchored in a foundation constructed below the shop floor. Such an arrangement is quite complicated and expensive.
In order to try to achieve a pumping station that does not need to be arranged under the floor level, yet still achieves an optimal or adequate conveying of the machining chips by means of a pump, German Utility Model Publication 295 105 14 U1 discloses a pumping system having a collecting container in the form of a cylindrical pot with an essentially flat planar container floor. A wiper or sweeper is provided to continuously run over the flat container floor in order to convey to the transport pump the machining chips that come to rest on the container floor. In such a known arrangement, the chips are continuously positively conveyed until just before the suction opening of the pump by the wiper or sweeper that is rotationally driven by a suitable drive arrangement. In order to contact, collect, and convey the chips and deliver them to the pump, the sweeper or wiper has sweeper arms that rest directly on the floor of the container. Nonetheless, some chips become caught between the top surface of the container floor and the bottom surface of the sweeper arms, and in this manner the sweeper arms become jammed against the container floor. In order to avoid this, the known arrangement further provides means for lifting the sweeper or the sweeper arms from the container floor. It has been found that this known arrangement is complicated and costly in its production and installation, and is also not very reliable in operation, due to the above described problems of the rotational sweeper or wiper and its drive arrangement, and especially due to the additional required means for avoiding jamming of the sweeper arrangement.